Home >>C Math Functions >C math cos() function
The C library function double cos(double x) is used to return the cosine of a radian angle x. It takes a single argument in radians and returns a value in type double in the range 1 to 1. This function is defined in <math.h> header file.
Syntax:double cos(double x);
x − It is the floating point value representing an angle expressed in radians.
Here is an example of cos() function:
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
double x, ret, val;
x = 60.0;
val = PI / 180.0;
ret = cos( x*val );
printf("The cosine of %lf is %lf degrees\n", x, ret);
return(0);
}
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
double x, ret, val;
x = 90.0;
val = PI / 180.0;
ret = cos( x*val );
printf("The cosine of %lf is %lf degrees\n", x, ret);
return(0);
}